This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Genes may play a strong role in prostate cancer etiology but epidemiological studies suggest that prostate cancer risk is largely determined by gene and environmental interactions. Increased attention should be placed on research in the African American population on environmental factors such as UV exposure (latitude, lifestyle and diet and their possible interactions with genetic loci. The goal of this project is to explore the effects of UV exposure, serum vitamin D, and skin color on prostate cancer risk in a large case-control study of African American men aged > 40 years from the Washington, DC area. Our specific aims are to (1) recruit 76 prostate cancer cases and 152 age and ethnicity matched controls;(2) assess UV exposure in African Americans prostate cancer patients and matched controls;(3) measure modifying factors of UV exposure (skin color, serum 25-OH Vitamin D, and genes involved in Vitamin D metabolism;(4) assessment of variation for genes involved in vitamin D metabolism;and (5) determine if UV exposure and modifying factors act alone or interact to affect prostate cancer risk in African Americans.